1. Technical Field
The present invention relates generally to seaming machines. More particularly, the invention relates to a seaming machine and method of seaming a number of sheet segments to form a larger sheet of material. Specifically, the invention relates to a bi-directional seaming machine which expedites the process of producing the seams between the sheet segments.
2. Background Information
The seaming together of multiple sheets of material is well known in the art. Typically, a first segment of sheet material is laid on a table or other work surface and a second segment of sheet material is positioned above the first segment with their edges generally aligned so that a seaming device moves along the aligned edges to forms a seam along the length of the two sheet segments. This typically results in a two-segment sheet which is roughly twice as large as each of the individual segments. In order to form larger sheets of material, additional segments of sheet material must be sequentially seamed together. This seaming process may be achieved by various seaming devices depending on the material from which the sheets are formed and the application for which the product will be used. For example, seams may be formed using plastic welders, ultrasonic welders, radio frequency (RF) welders, adhesive or glue seaming devices or sewing devices amongst others.
As will be appreciated, the larger the sheet becomes, the more unwieldy it is to handle. The standard practice for adding one or more additional segments of sheet material to the two-segment sheet is to slide one of the sheets segments off of the table or work surface and move the non-seamed edge of the other sheet segment adjacent the side of the table along which the seaming device is positioned. Especially during the formation of larger sheets of material such as relatively heavy tarps, the movement of these sheet segments and re-positioning thereof can easily require four or more people. Once the non-seamed edge of the second segment of sheet material is properly positioned, a third segment of sheet material is positioned adjacent the second segment and the edges of the second and third segments are then seamed together.
One type of plastic seaming machine utilizes a carriage on which the seaming device and associated structure are mounted so that it can roll back and forth along the edges of sheet material to be seamed together. However, the seaming device is only being used for seaming when the carriage is moving in a single direction. Thus, after seaming two segments of sheet material together, the carriage must be moved from one end of the seam to the other end of the seam in order to seam the next two segments of sheet material together. The relatively slow movement of the carriage back to its starting position is lost time in which no welding occurs. Considering the fact that some seams may be several hundred feet long, this lost time may be considerable. After each segment of sheet material is seamed to the previous one, additional sheet material must be moved off of the table or work surface and gradually piles up on the floor, often in disarray. Furthermore, material hanging off of the table or an elevated work surface pulls on the material atop the table and adds to the difficulty of aligning the material for a subsequent seaming operation. In short, the process is relatively time consuming and labor intensive.